Separation of zinc from aqueous samples using a molecular imprinting technique

In this article, the separation of zinc from aqueous samples by solid-phase extraction based on a molecular imprinting technique is described. Zn-imprinted polymer was prepared by free radical solution polymerisation in a glass tube containing ZnSO₄, morin, 4-vinylpyridine as a functional monomer, ethyleneglycoldimethacrylate as a cross-linking monomer, and 2,2′-azobisisobutyronitrile as an initiator. The obtained polymer block was ground and sieved (55–75 µm) and the Zn–morin complex was separated from polymer particles by leaching with 2M HCl. The synthesised polymer particles have been characterised by IR and differential scanning calorimetric studies either before or after leaching. The effects of different parameters, such as pH, adsorption and desorption time, type and minimum amount of the eluent for elution of the complex from polymer were evaluated. Extraction efficiency more than 99% was obtained by elution of the polymers with 10 mL of CH₂Cl₂–dimethyl sulfoxide (1 : 1, v/v). The detection limit of the proposed method was 2.9 µg L^?1. A dynamic linear range in the range of 25–200 µg L^?1 was obtained. The relative standard deviation was found to be below 9.2%. In addition, the influence of various cationic and anionic interferences on the complex recovery was studied. The method was applied to the recovery and determination of Zn in a few different real samples.